Comparison of US Oncologist Rurality by Practice Setting and Patients Served

This cross-sectional study assesses a method of classifying oncology physician rurality using proportion of rural patients served compared with a method based on practice location.


Introduction
2][3][4] Only about 3% of oncologists practice in a rural setting, 5 but workforce studies most often classify physician rurality by their practice location.This approach, given its high specificity, could miss the true extent of physicians involved in rural cancer care.Identifying the coordination that rural patients often face, including less access to routine health care, 6,7 less access to specialized cancer care, 8-10 and worse cancer survival and health outcomes. 11In this study, we aimed to develop a method for classifying physician rurality based on proportion of rural patients served, which could expand on methods using only practice setting.

Study Cohort
In this retrospective cross-sectional study, we used a 100% Centers for Medicare & Medicaid Services (CMS) file to identify beneficiaries with an incident diagnosis of breast (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] code C50.x), lung (ICD-10 code C34.x), or colorectal (ICD-10 codes C18.x, C19, and C20) cancer from January 1 to December 31, 2019, using an algorithm previously validated for Medicare claims data. 12Physicians caring for these patients were identified from CMS MedPAR and carrier files.Physician specialty was determined using the primary and first 2 subspecialty taxonomy codes in the National Plan and Provider Enumeration System, and we focused on medical oncologists, radiation oncologists, and surgeons who performed a cancer-related surgical procedure for cohort patients (eTable 1 in Supplement 1).This study followed the study design, analysis, and results reporting outlined by the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional studies.The project was approved by the Dartmouth College Committee for the Protection of Human Subjects, which waived the need for informed consent as an exempt study because it was determined to be secondary research of existing data reported in a manner that individuals could not be identified.

Rurality Classification
Rurality was assigned using Rural-Urban Commuting Area categorization B, which classifies codes as metropolitan, micropolitan, and rural (eTable 2 in Supplement 1). 13A 3-tier system was used for consistency with prior methods. 14Two methods were used to classify oncology physician rurality.
The first method was based on a physician's primary practice zip code, which was assigned based on the plurality of their encounters in the CMS carrier file.The second method involved a calculation of the percentage of patients who resided in a rural zip code who were seen by the physician.Patient rurality was determined from their residential zip codes in the Medicare Beneficiary Summary File.
We then conducted a subanalysis to expand who was classified as an oncologist practicing in a rural location, which addressed physicians practicing at multiple sites.Rather than using plurality of care, oncologists were categorized as practicing in a rural location if they provided any care in a rural setting.Among those who did not have any encounters in a rural setting, plurality of care was used to distinguish between predominantly metropolitan and micropolitan physicians.

Statistical Analysis
Data were analyzed from May to September 2023.We compared our new rurality classification method (ie, proportion of rural patients served) with the gold standard classification method (ie, practice location) using summary statistics, a receiver operating characteristic curve, and Cohen κ for multiple cutoff values.We summarized differences in characteristics between rural and urban oncology physicians using these methods for categorizing rurality.Location rurality was stratified into 3 bins: metropolitan, micropolitan, and rural.Rurality based on patient panel was stratified into no rural patients, low rural patient population (<20%), and 3 levels for high rural patient population (Ն20%, Ն33%, and Ն50%).Maps illustrated geographic differences in the distribution of the rural oncologist workforce using these 2 classification methods in the US.Analyses were performed using RStudio, version 4.3.1 (R Core Team).

JAMA Network Open | Oncology
Comparison of US Oncologist Rurality by Practice Setting and Patients Served

Results
The cohort included 27 870 oncology physicians, of whom 835 (3.0%) practiced in a rural location.
Among physicians who treated any rural patients, the patient panel consisted of a median of 16.7%  ).These observations were consistent after stratifying by specialist type (eTables 3-5 in Supplement 1) and when incorporating oncologists practicing at a secondary rural site (eTable 6 in Supplement 1).
Among oncology physicians practicing in a rural location, 529 of 835 (63.4%) had a patient panel of at least 50% (Table 3).Conversely, only 989 of 24 475 physicians (4.0%) practicing in a metropolitan location had a rural patient panel of at least 50%.Classifying oncologist rurality by their patient panel identified new areas across the US with rural providers (Figure 2), including in southern California, Maine, North Dakota, and Montana.

JAMA Network Open | Oncology
Comparison of US Oncologist Rurality by Practice Setting and Patients Served

Discussion
Rural patients with cancer can face unique challenges at all stages of their cancer journey from diagnosis to treatment to survivorship.Not only are rural patients affected by social and demographic contributors to cancer, which can lead to increased cancer risks and reduced survivorship, 15 these patients can also experience significant geographic disparities compared with their urban counterparts. 8,10There is a critical need to correctly identify which physicians are providing rural cancer care to better understand the true effects of rurality on disparities in care access and quality.
The characteristics of oncologists were consistent between the 2 rurality classification methods, but we identified differences in some characteristics between predominantly rural and predominantly metropolitan oncologists.Interestingly, we found that regardless of our classification method, predominantly rural oncologists were less likely to treat lung cancer, be a radiation oncologist, and be female.While uneven geographic distribution of oncology specialists has been established, more needs to be done to understand disparities for specific cancer types and oncology specialties. 10,16,17These rural disparities may be influenced by fewer training programs in rural areas, debt and salary concerns, or simply by limited access to specialized equipment to conduct complex therapy. 10,18

Figure 1 .
Figure 1.Comparison of Classifying Oncologist Physician Rurality Based on Practice Location vs Proportion of Rural Patients Served 1.0

Table 2 .
Characteristics of Rural and Urban Oncologists Using Methods of Classifying Oncologist Physician Rurality Based on Practice Location vs Proportion of Rural Patients Served a a Data are presented as number (percentage) of physicians unless otherwise indicated.bThese groups are not mutually exclusive.cOncologists could treat more than 1 cancer type.dCalculated as the number of years between National Provider Identifier enumeration date and January 1, 2019.

Table 3 .
Comparison of the Counts of Rural Oncologists Using Practice Location and Rural Patient Panel Figure 2. Distribution of Rural Oncologists in the US Using Methods of Classifying Oncologist Physician Rurality Based on Practice Location vs Proportion of Rural Patients Served Beltrán Ponce SE, Thomas CR, Diaz DA.Social determinants of health, workforce diversity, and financial toxicity: a review of disparities in cancer care.Curr Probl Cancer.2022;46(5):100893.doi:10.1016/j.currproblcancer.2022.10089316.Unger JM, Moseley A, Symington B, Chavez-MacGregor M, Ramsey SD, Hershman DL.Geographic distribution and survival outcomes for rural patients with cancer treated in clinical trials.JAMA Netw Open.2018;1(4):e181235.doi:10.1001/jamanetworkopen.2018.123517.Hung P, Deng S, Zahnd WE, et al.Geographic disparities in residential proximity to colorectal and cervical cancer care providers.Cancer.2020;126(5):1068-1076.doi:10.1002/cncr.3259418. Patterson DG, Shipman SA, Pollack SW, et al.Growing a rural family physician workforce: the contributions of rural background and rural place of residency training.Health Serv Res.Published online May 9, 2023.doi:10.1111/1475-6773.1416819.Yu L, Liu YC, Cornelius SL, et al.Telehealth use following COVID-19 within patient-sharing physician networks at a rural comprehensive cancer center: cross-sectional analysis.JMIR Cancer.2023;9:e42334.doi:10.2196/42334Taxonomy Codes Used to Classify Oncologist Specialty eTable 2. Rurality Categorization Based on Rural-Urban Commuting Area (RUCA) Codes eTable 3. Characteristics of Rural and Urban Medical Oncologists Using Two Rurality Classification Methods eTable 4. Characteristics of Rural and Urban Radiation Oncologists Using Two Rurality Classification Methods eTable 5. Characteristics of Rural and Urban Surgical Oncologists Using Two Rurality Classification Methods eTable 6. Characteristics of Rural and Urban Oncologists Incorporating Physicians Practicing at Multiple Sites a These groups are not mutually exclusive.A 33% Rural patient panel B 50% Rural patient panel C Rural practice location D 15.